New approaches to gravitational lensing

Details New approaches to gravitational lensing New approaches to gravitational lensing

Dec 2000

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2000phdt.........8k&link_type=abstract

Thesis (PhD). UNIVERSITY OF PITTSBURGH, Source DAI-B 61/06, p. 3093, Dec 2000, 109 pages.

Computer Science

1

Scientific paper

Two new approaches to gravitational lensing are developed and compared with the standard thin lens method. The first is an exact approach in which the time of flight and lens equations are found by explicitly integrating the null geodesic equation of a metric satisfying Einstein's equations. We consider Schwarzschild spacetime as a test model for the exact approach and derive equations for the exact observation angle of generic images, the observation angle of an Einstein ring, time delays, relative magnifications, and the angular-diameter distance. The exact method can be applied only in spacetimes which are exact solutions of Einstein's equations. Since many interesting lensing models are represented by approximate metrics, we introduce a pseudo ``exact'' method where the time of flight and lens equations are found by numerically integrating the exact null geodesic equations of the approximate metric. As a second new approach, we develop an iterative method for gravitational lensing which can be implemented in any geometry close to one in which the null geodesics of a metric satisfying Einstein's equations can be found exactly. The iterative method takes the thin lens trajectory as its zeroth-iterate and can be considered as a correction to the thin lens approximation. Taking the pseudo ``exact'' method to represent true or correct values, we examine the accuracy of the thin lens and iterative methods. Our central question is whether the inherent errors in the thin lens approximation are comparable in size to observational errors today or corrections in model building. We find that there are significant errors in the thin lens approximation when there are two monopole lenses separated by a distance which is small compared to the distance between the observer and either lens but large compared to the relevant impact parameter. In this range we show that the iterative method remains very accurate.

Affiliated with

Also associated with

No associations

Rating

New approaches to gravitational lensing does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with New approaches to gravitational lensing, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and New approaches to gravitational lensing will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1160089